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A study of presence of accessory foramina transversaria in dry human cervical vertebrae of South Indian origin.

INTRODUCTION

The unique feature seen in the cervical vertebrae is the presence of foramina transversaria in the transverse processes of all the cervical vertebrae. In all except the seventh cervical vertebra, the foramen transversarium (FT) normally transmits the vertebral artery and vein and a branch from cervicothoracic ganglion (vertebral nerve). [1] The foramina transversaria are known to exhibit variations in their shape, size, and in number. Sometimes, there may be multiple FT or they may be absent. Etiology of such variations may be related to variations in the course of vertebral artery or may be related to development. [2] An accessory transverse foramen (AFT) is present as a smaller foramen posterior to the FT. [3] As a result, distortion of the course of vertebral artery may occur. The above variations in FT can cause complaints such as headache, migraine attacks, and fainting. [4]

Knowledge of anatomical variations of cervical spine is vital for surgical procedures that involve the screw fixation. The risk of damage to vertebral artery during surgical procedures increases in cases of osseous and vascular variations of cervical spine. [5] The anatomical knowledge of variations of FT is important for the clinicians, neurologists, neurosurgeons, and radiologists. [2]

There are enough studies and case reports regarding variations in the origin and course of vertebral artery. Relatively, fewer studies are available on the morphology and incidence of the AFT, especially in Southern India. Hence, the present study was undertaken with the objective to find out the incidence of accessory foramina transversaria (AFT) in the cervical vertebrae of South Indian origin.

MATERIALS AND METHODS

Analytical and cross-sectional study was performed on 100 adult dry cervical vertebrae of unknown age and sex. The study was carried out in the Department of Anatomy, Amala Institute of Medical Sciences, Thrissur, Kerala, India. 100 dried human cervical vertebrae were selected for study after excluding damaged and pathologically abnormal vertebrae from the department of anatomy. Of 100 cervical vertebrae, 45 were atypical (C1, C2, and C7) and 55 were typical cervical vertebrae (C3, C4, C5, and C6). All the vertebrae were macroscopically examined for the presence of AFT. Vertebrae having AFT unilaterally or bilaterally were separated and photographed. The data were compiled and descriptive analysis was done using Microsoft Excel software.

As the study was observational and done on dry human bones, ethical clearance was not required.

RESULTS

Of examined 100 (including both typical and atypical) cervical vertebrae, 20 vertebrae have shown the presence of AFT. Of 20 vertebrae, 12 were having unilateral AFT [Figure 1] and eight were having bilateral AFT [Figure 2]. The percentage of AFT was shown in Table 1.

Of 100 cervical vertebrae, 55 were typical vertebrae (C3, C4, C5, and C6). The incidence of AFT in these vertebrae was shown in Table 2.

Of 100 cervical vertebrae, 45 were atypical vertebrae (C1, C2, and C7). The incidence of AFT in these vertebrae was shown in Table 3.

DISCUSSION

From the observations as per the above tables, it was inferred that the presence of AFT was more common in typical cervical vertebrae as compared to atypical vertebrae. Unilateral AFT was more commonly seen. In the present study, atypical cervical vertebrae, namely C1 and C2, have not shown AFT at all. C7 vertebrae showed only unilateral AFT.

Developmentally, vertebrae form from the sclerotome portions of the somites, which are derived from paraxial mesoderm. The transverse processes of cervical vertebrae are directed laterally and slightly forward. Each transverse process presents an opening called FT. The FT is bounded by anterior root and anterior tubercle, costotransverse bar, posterior tubercle, and posterior root in order. The costal element is represented by anterior root, anterior tubercle, costotransverse bar, posterior tubercle, and distal part of the posterior root. Proximal part of the posterior root represents the true transverse element. Developmentally, FT is formed by fusion vestigial costal element and true transverse process of the cervical vertebra. The vertebral vessels and nerve plexuses are caught between these two bony elements. Developmentally, vertebral arteries are formed from cervical intersegmental arteries which arise from the dorsolateral aspect of the dorsal aorta. These arteries link up with one another and form the longitudinal anastomotic channels, except the seventh cervical intersegmental artery. Remaining arteries regress and modified to form the vertebral artery. [6] When there is failure in controlled regression, it leads to variations in the vertebral artery origin and course. As the vertebral artery passes through FT, variations in vertebral artery might lead to variations in foramen. Hence, it can be interpreted that the variations in the course of the vertebral arteries will lead to variations in FT. [7]

AFT may be unilateral or bilateral, in the present study, we observed that the incidence of AFT in cervical vertebrae was 20%, of which unilateral AFT was 12% and bilateral AFT was 8%. In Table 4, the incidence of the AFT in the present study was compared with various other studies.

From Table 4, we can see that incidence of AFT varies from 1.5% to 27.33%. A study done by Das et al., [2] on 132 vertebrae, it was observed double foramina transversaria unilaterally and bilaterally only in two cervical vertebrae, respectively. However, Taitz et al. [7] from their study observed doubling of FT in 34 cases of 480 cervical vertebrae amounting to 7%. In the same study, it was also reported triple foramina transversaria in one vertebra and absent foramen in four vertebrae. [7] In the present study, 20 vertebrae showed AFT of 100, and we did not observe more than one AFT. In the present study, we also observed that the incidence of AFT is more in typical cervical vertebrae as compared to atypical. Of 133 cervical vertebrae studied by Chaudhari et al., [14] double foramina transversarium was observed in 22 vertebrae (23.15%), of which unilateral double foramen was found in 14 vertebrae (14.73%), and the bilateral was found in 8 vertebrae (8.42%). The above results were more in conformity with our study. Compared to other South Indian studies done by Murlimanju et al., [8] Ambali MP et al., [13] Sumalatha and Manasa, [17] and Katikireddi et al., [18] the present study results were more in line with the North Indian studies such as Patra et al. [16] and Choudhari et al. [14] Knowledge of variations in the morphology of FT in cervical vertebrae is clinically important because the course of the vertebral artery may be distorted under such condition. Even the presence of extraforaminal in the transverse processes may indicate multiplication of the number of structures running through them. Hence, understanding of such anatomical variations is very much relevant for clinicians, surgeons, and radiologists.

Limitations

The sample size was small, limited to 100 vertebrae.

CONCLUSION

The incidence of AFT in the present study was 20%. AFT was more common in typical cervical vertebrae as compared to atypical vertebrae. Unilateral AFT was more commonly seen than bilateral AFT. The first and second cervical vertebrae (atypical) have not shown AFT at all. Among the atypical vertebrae, only the seventh vertebra showed unilateral AFT. A thorough knowledge of these variations will be helpful to clinicians, radiologists, and neurosurgeons.

REFERENCES

[1.] Standring S, Gray H. Gray's Anatomy. 40th ed. Edinburgh: Churchill Livingstone/Elsevier; 2008. p. 718-20.

[2.] Das S, Suri R, Kapur V. Double foramen transversaria: An osteological study with clinical implications. Int Med J 2005;12:311-3.

[3.] Bergman RA, Thompson SA, Afifi AK, Saadeh FA. Compendium of Human Anatomic Variation. Germany: Urban & Schwarzenberg; 1988. p. 197.

[4.] Caovilla HH, Gananca MM, Munhoz MS, Silva ML, Gananca FF, Silva ML, et al. Sindrome Cervical. Quadros Clinicos Otoneurologicos Mais Comuns. Sao Paulo: Atheneu; 2000. p. 95-100.

[5.] Bridwell KH, Anderson PA, Boden SD, Vaccaro AR, Wang JC. What's new in spine surgery. J Bone Joint Surg Am 2008;90:1609-19.

[6.] Datta AK. Essentials of human embryology. 6th ed. Kolkata: Current Books International; 2010. p. 183.

[7.] Taitz C, Nathan H, Arensburg B. Anatomical observations of the foramina transversaria. J Neurol Neurosurg Psychiatry 1978;41:170-6.

[8.] Murlimanju BV, Prabhu LV, Shilpa K, Rai R, Dhananjaya KV, Jiji PJ, et al. Accessory transverse foramina in the cervical spine: Incidence, embryological basis, morphology and surgical importance. Turk Neurosurg 2011;21:384-7.

[9.] Shah ST, Arora K, Shah KP. Study of accessory foramen transversarium in cervical vertebrae. GCSMC J Med Sci 2014;3:1-5.

[10.] Sharma A, Singh K, Gupta V, Srivastava S. Double FT. Double foramen transversarium in cervical vertebra an osteological study. J Anat Soc India 2010;59:229-31.

[11.] Gujar SM, Oza SG, Shekhawa JP. A study of accessory foramen transversarium in dry cervical vertebrae and its clinical implications. NJIRM 2015;6:27-30.

[12.] Akhtar MJ, Madhukar PK, Rahman S, Kashyap N. A morphometric study of foramen transversarium of dried cervical vertebrae. Int J Res Med Sci 2015;3:912-6.

[13.] Ambali MP, Jadhav ST. Anatomical variations in foramen transversarium of typical cervical vertebrae and its clinical significance. Int J Anat Res 2017;5:3426-9.

[14.] Chaudhari ML, Maheria PB, Bachuwar SP. Double foramen transversarium in cervical vertebra. Morphology and clinical importance. Indian J Basic Appl Med Res 2013;8:1084-8.

[15.] Mishra GP, Bhatnagar S, Singh B, Mishra PP, Mishra A. Anatomical variations in foramen transversarium of typical cervical vertebrae and clinical significance. Int J Biomed Res 2014;5:405-7.

[16.] Patra A, Kaur H, Chhabra U, Kaushal S, Kumar U. Double foramen transversarium in dried cervical vertebra: An osteological study with its clinical implications. Indian J Oral Sci 2015;6:7-9.

[17.] Sumalatha T, Manasa B. Variations in foramen transversarium of cervical vertebrae-an observational study. Int J Anatomy Radiol Surg 2018;7:13-7.

[18.] Katikireddi RS, Setty SN. A study of double foramen transversarium in dried cervical vertebra. Int J Health Sci Res 2014;4:59-61.

Motagi Vishwanath Manjunath (1), Dharwadkar Kavitarati (2), Kottapurath Raghavan Sugathan (1)

(1) Department of Anatomy, Amala Medical College, Amala Nagar, Thrissur, Kerala, India, (2) Department of Biochemistry, Amala Medical College, Amala Nagar, Thrissur, Kerala, India

Correspondence to: Motagi Vishwanath Manjunath, E-mail: drmanjunathm@gmail.com

Received: August 21, 2018; Accepted: September 12, 2018

DOI: 10.5455/ijmsph.2018.0925712092018

Caption: Figure 1: Unilateral accessory foramen transversarium

Caption: Figure 2: Bilateral accessory foramen transversarium
Table 1: Percentage of AFT in cervical vertebrae

Total number of      Number of   Unilateral   Bilateral
cervical vertebrae   vertebrae      AFT          AFT
                     with AFT

N = 100              20 (20%)     12 (12%)     8 (8%)

AFT: Accessory foramen transversarium

Table 2: Percentage of AFT in typical cervical vertebrae

Total number of     Number of    Unilateral   Bilateral
typical cervical    vertebrae       AFT          AFT
vertebrae           with AFT

55                 16 (29.09%)   8 (14.54%)   8 (14.54%)

AFT: Accessory foramen transversarium

Table 3: Percentage of AFT in atypical
cervical vertebrae

Total number of atypical    Number of    Unilateral   Bilateral
cervical vertebrae N=45     vertebrae       AFT          AFT
                             with AFT

C1                              0            0            0
C2                              0            0            0
C7                              4        4 (8.88%)        0

AFT: Accessory foramen transversarium

Table 4: Comparison of incidence of AFT with other studies

Authors                Number of   Incidence    Unilateral   Bilateral
                       cervical    of AFT (%)    AFT (%)      AFT (%)
                       vertebrae

Das et al. [2]            132         1.5           --          --
Taitz et al. [7]          480          7            --          --
Murlimanju et             363         1.60         1.40        0.30

  al. [8]
Shah et al. [9]           210        16.19         9.52        6.67
Sharma et al. [10]        200          8           3.50        4.50
Gujar et al. [11]         150        27.33          18         9.33
Akhtar et al. [12]        174        14.36        11.49        2.87
Ambali MP et              163        14.72         4.90        9.81
  al. [13]
Chaudhari et              133        23.15        14.73        8.42
  al. [14]
Mishra et al. [15]        220        14.09         4.54        9.54
Patra et al. [16]         150          22         10.67        11.33
Sumalatha and             148        11.48         5.40        6.08
  Manasa [17]
Katikireddi et            100          3            2            1
  al. [18]
Present study 2018        100          20           12           8

AFT: Accessory foramen transversarium
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Title Annotation:Research Article
Author:Manjunath, Motagi Vishwanath; Kavitarati, Dharwadkar; Sugathan, Kottapurath Raghavan
Publication:International Journal of Medical Science and Public Health
Article Type:Report
Geographic Code:9INDI
Date:Nov 1, 2018
Words:1980
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